Heretofore, when a road surface got wet at the time of a rainy weather season and a frictional force between the road surface and a tire degraded, slip might arise at the time of brakes being applied, a motor vehicle might move in an unexpected direction, and an accident might be caused.
In order to prevent an accident which arose by such a slip, quick start, and the like, an anti-lock brake system (hereafter, this is called an ABS), a traction control system, and further, a stability control system, which a YAW sensor was provided, and the like have been developed.
For example, the ABS is a system which detects a rotation state of each tire and controls a braking force to prevent each tire from entering into a locked state on the basis of this detection result.
It is possible to detect states such as rotating speed, air pressure, and strain of each tire as rotation states of tires and to use this detection result for control.
As examples of such a control system, for example, what are known are a motor vehicle braking apparatus disclosed in Japanese Patent Publication (Hei)05-338528 (hereafter, this is called patent document 1), a brake control apparatus disclosed in Japanese Patent Publication 2001-018775 (hereafter, this is called patent document 2), a motor vehicle control method and an apparatus thereby disclosed in Japanese Patent Publication 2001-182578 (hereafter, this is called patent document 3), a motor vehicle motion control system disclosed in Japanese Patent Publication 2002-137721 (hereafter, this is called patent document 4), a braking system disclosed in Japanese Patent Publication 2002-160616 (hereafter, this is called patent document 5), and the like.
What is disclosed in the patent document 1 is the braking system which prevents the change of brake pedal feeling on brake operation at the time of rapid brake operation and brake operation immediately after that by controlling a pump motor so that a vacuum pump operates when decelerated acceleration of a motor vehicle has reached a predetermined value is detected by an acceleration sensor 14 by negative pressure being supplied from a vacuum tank to a vacuum booster connected to a brake pedal, negative pressure being supplied from the vacuum pump to this vacuum tank, and this vacuum pump being driven by the pump motor.
What is disclosed in the patent document 2 is the brake control system in a brake control system provided with control means executing ABS control, wherein the control means comprises lateral acceleration estimating means of estimating lateral acceleration generated in a motor vehicle, and comparison test means of comparing estimated lateral acceleration by this lateral acceleration estimating means, estimated lateral acceleration by vehicle behavior detecting means, and detected lateral acceleration which a lateral acceleration sensor included in the vehicle behavior detecting means detects, judging that a normal turn corresponding to a turning angle is being performed, when difference between both is under a predetermined value, and judging that an abnormal turning is being performed, when the above-mentioned difference is not less than the predetermined value, and wherein control is switched between the cases of the judgment of the normal turn and the judgment of the abnormal turn during ABS control of the above-mentioned control means.
What is disclosed in the patent document 3 is the motor vehicle control method and apparatus thereby in a motor vehicle control method where a control signal for adjusting the deceleration and/or acceleration of a motor vehicle is formed by a corresponding setting value, and an apparatus thereby, wherein a correction coefficient denoting motor vehicle acceleration or motor vehicle deceleration generated by a traveling road surface inclination is formed, this correction coefficient is superimposed with a setting value, and the setting of the motor vehicle deceleration and/or acceleration is improved.
What is disclosed in the patent document 4 is the motor vehicle motion control apparatus which acquires side slip angle changing speed β′ of a center of gravity as an actual yawing motion state function of a motor vehicle which has a plurality of wheels, generates yawing moment, whose value becomes large as the value becomes large and whose direction decreases an absolute value of the changing speed β′, whose by making brake fluid pressure ΔP act on either of left and right rear wheel brakes when the absolute value of the changing speed β′ is not less than a setting value β0′, continues judgment of whether slip control is necessary in a wheel on which the brake fluid pressure ΔP is made to act, also in this yawing moment control, and performs slip control of keeping a slip ratio in a proper range by suppressing brake fluid pressure ΔP when the slip control is required.
What is disclosed in the patent document 5 is the braking apparatus, which comprises at least two out of an acceleration sensor detecting acceleration in a fore-and-aft direction of a motor vehicle, a wheel speed sensor detecting the wheel speed of each wheel, and a braking pressure sensor detecting braking pressure, and which can suppress output abnormality even if a disturbance arises or one sensor breaks down, by calculating target braking pressure by feedback from the at least two sensors, calculating an indicator current in an indicator current arithmetic section on the basis of this operation result, flowing the indicator current to a brake drive actuator, and generating a braking force depending on the amount of the indicator current.
In addition, what is common as a method of detecting the rotating speed of a tire is a method of detecting the rotating speed of a tire by a rotor A1, rotating with being integrated with a wheel carrier, and a pickup sensor A2 as shown in FIGS. 38 and 39. In this method, flux density varies because a plurality of irregularities provided in a circumferential surface of the rotor A1 at equal intervals crosses a magnetic field generated by the pickup sensor A2, and a pulse-like voltage arises in a coil of the pickup sensor A2. It is possible to detect rotating speed by detecting this pulse. An example of a basic principle of this method is disclosed in Japanese Patent Publication (Sho)52-109981.